Criticality Data for Spherical {sup 235}U, {sup 239}Pu, and {sup 237}Np Systems Reflector-Moderated by Low Capturing-Moderator Materials
- Los Alamos National Laboratory (United States)
The critical dimensions of spherical systems moderated and reflected by low-capturing materials such as D{sub 2}O, BeO, Be, and C were investigated. A parametric study of the critical mass of enriched uranium, plutonium, and neptunium is examined and tabulated. The results obtained expand on the understanding of reflector-moderated critical systems, and they show regions of unstable criticality for {sup 235}U and {sup 239}Pu reflected cores at intermediate densities. This instability is illustrated by calculations of the positive reactivity coefficient of volume expansion. The coefficient is positive, not negative, in the intermediate density region for {sup 235}U and {sup 239}Pu systems. For {sup 237}Np cores reflected by the same moderator, the effect is negligible. The critical dimensions were calculated with the DANTSYS codes using the Hansen-Roach cross-section libraries. This study is both a summary of mostly unpublished calculations and new calculations. Experimental data for these configurations are extremely limited. These are examined in the text when applicable.
- OSTI ID:
- 20840203
- Journal Information:
- Nuclear Technology, Vol. 146, Issue 2; Other Information: Copyright (c) 2006 American Nuclear Society (ANS), United States, All rights reserved. http://epubs.ans.org/; Country of input: International Atomic Energy Agency (IAEA); ISSN 0029-5450
- Country of Publication:
- United States
- Language:
- English
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